Increasing prices of fossil fuels and petroleum products has, to a large extent, resulted in the production of hydrogen and ethanol, as well as other fermentation products, from plant biomass becoming an increasingly attractive option for alternative fuel production. The production of such alternative fuels is also important for countries that lack oil or coal.
In addition, hydrogen is recognized as a clean and recyclable energy carrier. Consequently it is considered to be one of the major energy sources in the future and much effort has been expended on exploring methods of sufficiently and efficiently supplying hydrogen. Furthermore, biological production of hydrogen from organic wastes as well as from other recyclable resources is considered preferable to the production of hydrogen from food crops for, while the hydrogen yield of food crops such as maize and wheat is relatively high, there is a global food shortage which is in danger of becoming exacerbated by the use of food crops in biological hydrogen producing reactors.
Currently no suitable bioreactor apparatus or methodology is known to the inventor for the rapid screening, selection and isolation of biofilm, floc and granule forming thermophilic bacteria or bacteria consortia that generate high levels of hydrogen from plant biomass including the soluble hydrolysates derived from the hydrolysis of cellulosic materials and particularly of cellulosic materials such as sugar cane waste and effluent that been subjected to only minimum pretreatment such as milling and wet heating.
Thermophiles, including extreme thermophiles, have many advantages as agents for the generation of biohydrogen from cellulose and from soluble hydrolysate derived from cellulose hydrolysis. Perhaps their main advantage is that high temperatures exclude microbial contamination from a bioreactor system. High temperature also shift the equilibrium constant for the hydrogen generating reactions in the forward direction thereby increasing the hydrogen yield. Most thermophiles and extreme thermophiles are, however, difficult to culture and maintain as pure cultures although it has been found that the hydrolysis of cellulosic materials and the generation of hydrogen from the products of this hydrolysis becomes increasingly favourable under the action of a mixed consortium of bacteria that includes anaerobic cellulolytic bacterial species.